Reversal device for Li-ion cell overcharge protection

Abstract

A lithium-ion battery cell includes a casing, a first terminal pad having a first polarity and positioned proximate the casing, a second terminal pad having a second polarity opposite to the first polarity and positioned proximate the casing, and a reversal device formed into the casing and responsive to an increase in internal pressure within the casing so as to cause a short circuit between the first terminal pad and the second terminal pad when the internal pressure reaches a threshold. The reversal device has a folded configuration and an unfolded configuration, and is configured to transition from the folded configuration to the unfolded configuration in response to an increase in the internal pressure from below the threshold to the threshold.

The invention claimed is: 
     
       1. A lithium-ion battery cell, comprising:
 a casing; 
 a first terminal pad having a first polarity and positioned proximate the casing; 
 a second terminal pad having a second polarity opposite to the first polarity and positioned proximate the casing; 
 an reversal device formed into the casing and extended along a plane coplanar with respect to a surface of the casing, the reversal device positioned to be responsive to an increase in internal pressure within the casing and with a portion on the reversal device configured to directly contact the first terminal pad and the second terminal pad upon the internal pressure within the casing reaching a threshold to cause a short circuit between the first terminal pad and the second terminal pad when the internal pressure reaches the threshold; 
 a first ridge positioned between a stationary perimeter portion and a movable central portion of the reversal device, the stationary perimeter portion of the reversal device extending from the first ridge, outwardly away from the movable central portion of the reversal device with the extension from the first ridge away from the movable central portion being at a decline towards an interior of the lithium-ion battery cell and to the plane, the first ridge having a notch positioned towards an interior of the lithium-ion battery cell, with the first ridge having the notch being a first flex point; 
 the movable central portion of the reversal device contiguous with the stationary perimeter portion at the first ridge and comprising a center and a frustum surrounding the center, the center and the frustum contiguous at a second ridge, with the second ridge being a second flex point, with the center adjustable with respect to the frustum at the second flex point, wherein the frustum and the stationary perimeter portion are oriented crosswise relative to one another, and the frustum extended from the first ridge toward the interior of the lithium-ion battery cell; and 
 the first flex point and the second flex point coordinated to facilitate transitioning of the reversal device from a folded configuration to an unfolded configuration. 
 
     
     
       2. The lithium-ion battery cell of  claim 1 , wherein the center of the movable central portion is a disk. 
     
     
       3. The lithium-ion battery cell of  claim 1 , wherein the portion on the reversal device configured to directly contact the first terminal pad and the second terminal pad comprising a conductor positioned on top of the center of the movable central portion, wherein the reversal device is configured to move the conductor into contact with the first terminal pad and the second terminal pad in response to the internal pressure reaching the threshold. 
     
     
       4. The lithium-ion battery cell of  claim 1 , wherein the reversal device is configured to transition from the folded configuration to the unfolded configuration in response to an increase in the internal pressure from below the threshold to the threshold. 
     
     
       5. The lithium-ion battery cell of  claim 1 , wherein the reversal device comprises a vent for the lithium-ion battery cell. 
     
     
       6. The lithium-ion battery cell of  claim 1 , wherein the stationary perimeter portion and the frustum are joined at the first ridge. 
     
     
       7. The lithium-ion battery cell of  claim 1 , wherein the first terminal pad is electrically coupled to a positive electrode of the lithium-ion battery cell, and the second terminal pad is electrically coupled to a negative electrode of the lithium-ion battery cell. 
     
     
       8. The lithium-ion battery cell of  claim 1 , wherein the casing and the reversal device are formed from aluminum. 
     
     
       9. A lithium-ion battery module comprising:
 a housing; 
 a plurality of lithium-ion battery cells positioned within the housing, wherein each lithium-ion battery cell of the plurality of lithium-ion battery cells comprises a casing, a first terminal pad having a first polarity and positioned proximate the casing, a second terminal pad having a second polarity opposite to the first polarity and positioned proximate the casing, and an reversal device formed into the casing and extended along a plane coplanar with respect to a surface of the casing and responsive to an increase in internal pressure within the casing with a portion on the reversal device configured to contact the first terminal pad and the second terminal pad upon the internal pressure reaching a threshold, while the reversal device remaining in one-piece construction, so as to cause a short circuit between the first terminal pad and the second terminal pad when the internal pressure reaches the threshold; 
 a ridge positioned between a stationary perimeter portion and a movable central portion of the reversal device, the stationary perimeter portion of the reversal device extending from the ridge, outwardly away from the movable central portion of the reversal device with the stationary perimeter portion extended from the ridge with the extension from the ridge away from the movable central portion being at a decline towards an interior of the lithium-ion battery cell to the plane, the ridge having a notch positioned towards an interior of the lithium-ion battery cell, with the ridge having a notch being a first flex point; 
 the movable central portion of the reversal device is contiguous with the stationary perimeter portion at the ridge and comprises a center and a frustum surrounding the center, the center and the frustum in connection at a second flex point, with the center adjustable with respect to the frustum at the second flex point, wherein the frustum and the stationary perimeter portion are oriented crosswise relative to one another, and the frustum extended from the ridge toward the interior of the lithium-ion battery cell; and 
 the ridge having a notch positioned towards the interior of the lithium-ion battery cell, with the notch configured to facilitate transitioning of the reversal device from a folded configuration to an unfolded configuration. 
 
     
     
       10. The lithium-ion battery module of  claim 9 , wherein the center of the movable central portion is a disk. 
     
     
       11. The lithium-ion battery module of  claim 9 , wherein the portion on the reversal device configured to directly contact the first terminal pad and the second terminal pad comprising a conductor positioned on top of the center of the movable central portion, wherein the reversal device is configured to move the conductor into contact with the first terminal pad and the second terminal pad in response to the internal pressure reaching the threshold. 
     
     
       12. The lithium-ion battery module of  claim 9 , wherein the reversal device is configured to transition from the folded configuration to the unfolded configuration in response to an increase in the internal pressure from below the threshold to above the threshold. 
     
     
       13. The lithium-ion battery module of  claim 9 , wherein the reversal device comprises a vent for each lithium-ion battery cell of the plurality of lithium-ion battery cells. 
     
     
       14. The lithium-ion battery module of  claim 9 , wherein the stationary perimeter portion and the frustum are joined at the ridge. 
     
     
       15. A lithium-ion battery cell, comprising:
 a casing; 
 a first terminal pad having a first polarity and positioned proximate the casing; 
 a second terminal pad having a second polarity opposite to the first polarity and positioned proximate the casing; 
 an reversal device formed coplanar to, and in extension along, a surface of the casing, and having a stationary perimeter portion extended in a direction outwardly away from a first ridge and a movable central portion of the reversal device at a decline towards an interior of the lithium-ion battery cell to a base plane, and responsive to an increase in internal pressure within the casing so as to cause a short circuit between the first terminal pad and the second terminal pad when the internal pressure reaches a threshold with a conductor of the reversal device configured to directly contact the first terminal pad and the second terminal pad upon the internal pressure reaching the threshold; 
 the reversal device comprises a folded configuration and an unfolded configuration, wherein the reversal device is configured to transition from the folded configuration to the unfolded configuration in response to an increase in the internal pressure from below the threshold to the threshold; 
 the first ridge positioned between the stationary perimeter portion and the movable central portion of the reversal device and a notch in the first ridge where the stationary perimeter portion and the movable central portion are joined, positioned towards an interior of the lithium-ion battery cell, configured to facilitate the transition at a first flex point; and 
 the movable central portion having a center and a frustum contiguous at a second ridge, with the second ridge being a second flex point for the transition. 
 
     
     
       16. The lithium-ion battery cell of  claim 15 , wherein the reversal device comprises the stationary perimeter portion and the movable central portion that are coextensive with one another, and wherein the folded configuration of the reversal device has the stationary perimeter portion and the movable central portion oriented crosswise relative to one another. 
     
     
       17. The lithium-ion battery cell of  claim 16 , wherein the unfolded configuration of the reversal device has the stationary perimeter portion and the movable central portion oriented parallel to one another. 
     
     
       18. The lithium-ion battery cell of  claim 17 , comprising:
 the conductor positioned on top of the movable central portion, wherein the reversal device is configured to move the conductor into contact with the first terminal pad and the second terminal pad in response to the internal pressure reaching the threshold.